1. Field of the Invention
The present invention relates to a method of configuring a network topology when a new entry node joins a ring network which is constituted by a plurality of nodes. The present invention also relates to a node constituting a part of a ring network which is constituted by a plurality of nodes, and a node newly joining the ring network.
2. Description of the Related Art
Referring to FIGS. 1 to 5, a conventional network topology configuring method (a method used in the “Gnutella”) will be described. In particular, operations for a node 105 to newly join a network including nodes 101 to 104 will be described.
First, as shown in FIG. 1, the node 105 establishes a connection with, among the nodes 101 to 104 constituting the network, the node 101 whose IP address or universal resource locator (URL) it knows.
Second, as shown in FIG. 2, the node 105 transmits a Ping message including the IP address of the node 105 to the node 101.
Third, as shown in FIG. 3, the node 101 returns a Pong message including the IP address of the node 101 to the node 105, and also transfers the Ping message including the IP address of the node 105 to the nodes 102 to 104.
Fourth, as shown in FIG. 4, the nodes 102 to 104 return Pong messages including their respective IP addresses to the node 105.
Repetition of the above procedure allows the node 105 to obtain the IP addresses of the nodes within the range specified in the time to live (TTL) field in the Ping message.
Fifth, as shown in FIG. 5, the node 105 establishes connections with the nodes 101 to 104 constituting the network, referring to their IP addresses included in the received Pong messages.
As a result, the node 105 can newly join the network constituted by the nodes 101 to 104.
In the conventional network topology configuring method, the new entry node 105 is configured to use Ping and Pong messages to randomly join a network, as described above.
The conventional network topology configuring method, however, has a problem in that the new entry node 105 has difficulty in quickly finding the positional relationships between the nodes in the network it has entered, and takes time to obtain network topology configuration information on each node constituting a part of the network.
The conventional network topology configuring method causes many links between nodes constituting a network. When a node failure or disengagement of a node from the network occurs, a number of messages are exchanged between adjacent nodes for update of network topology configuration information including information about the links. This causes the problem in that the network load is increased, and the nodes need time to update network topology configuration information.